Simultaneous multi-mode and multi-band ultrasonic imaging

ABSTRACT

An ultrasound imaging method and system configured to simultaneously acquire and process multi-mode and multi-band echo information from a single set of pulse firings. Raw ultrasound signals are digitized and stored in an I/Q data buffer. The stored data are then parallel preprocessed as a function of frequency band or alternative encoding. Parallel preprocessing optionally includes manipulating the data in respect to different imaging modes. Outputs of the parallel preprocessors are coupled to separate echo formers used to simultaneously reconstruct various desired echo information to form a multi-mode or multi-band image. The echo formation process is optionally preformed in parallel.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application is related to U.S. patent application Ser. No.______, entitled “Block Switching in Ultrasound Imaging,” filed on Oct.18, 2001. The subject matter of the related applications is herebyincorporated by reference. The related applications are commonlyassigned.

BACKGROUND

[0002] 1. Field of the Invention

[0003] The invention is in the field of imaging devices and moreparticularly in the field of ultrasonic imaging.

[0004] 2. Description of the Prior Art

[0005] Ultrasonic imaging is a frequently used method for examining awide range of materials. The method is especially common in medicinebecause of its relatively non-invasive nature, low cost, and fastdiagnostic cycles. Typically, ultrasound imaging is accomplished bygenerating and directing ultrasonic sound waves into a material underinvestigation and then observing reflections generated at the boundariesof dissimilar materials. The reflections are converted to electricalsignals by receiving devices (transducers) and then processed, usingbeam-forming techniques known in the art, to determine the locations ofecho sources. The resulting data is displayed using a display devicesuch as a monitor.

[0006] Typically, the ultrasonic signal transmitted into the materialunder investigation is generated by applying continuous or pulsedelectronic signals to a transducer. The transmit frequency of medicalultrasound is most commonly in the range of 1 MHz to 15 MHz. Theultrasound propagates through the material under investigation andreflects off of structures such as boundaries between adjacent tissuelayers. As it travels, the ultrasonic energy may be scattered,resonated, attenuated, reflected, or otherwise modified. Portions of thereflected signals are returned to the transducers and detected asechoes. The detecting transducers convert the echo signals to electronicsignals and furnish them to a beamformer. The beamformer calculateslocations of echo sources and typically includes simple filters andsignal averagers. Calculated positional information, produced through aserial series of beam-forming operations, is used to generatetwo-dimensional data that can be presented as an image. In prior artsystems, the rate at which images are formed (the frame rate) is limitedby at least the pulse return time. The pulse return time is the timebetween the transmission of ultrasonic sound into the media of interestand the detection of the last reflected signals.

[0007] As an ultrasound pulse propagates through a material underinvestigation, additional harmonic frequency components are generated.These additional harmonic frequency components continue to propagateand, in turn, reflect off of or interact with other structures in thematerial under investigation. Both fundamental and harmonic signals aredetected. The analysis of harmonic signals is generally associated withthe visualization of boundaries or image contrast agents designed tore-radiate ultrasound at specific harmonic frequencies.

[0008] Several modes of ultrasonic imaging are established in the priorart. These prior art modes include analyzing signals at the fundamental(base-band) or harmonic frequencies for studying static structures inthe material under investigation, and detecting movement using spectralDoppler or color Doppler imaging modes. These imaging modes are eithersequentially or alternatively executed and the results combined in asingle image. For example, in one prior art system a first series ofultrasound pulses is first fired to facilitate tissue harmonic imagingthat is utilized to examine a human heart. A second series of ultrasoundpulses is fired to generate color Doppler imaging signals at afundamental frequency. These signals measure the velocity of blood flowthrough the heart. The first series and second series of ultrasoundpulses are alternated in a line-interleaved or frame-interleaved manner.The signals generated by each series are analyzed separately and theresulting two-dimensional data is combined in a single data set fordisplay to the user. In the display it is common to use color todifferentiate and characterize the combined data sets. Since the dataare recorded using two different sets of ultrasound pulses, generated atdifferent times, the displayed image may contain undesirable temporalanomalies. For example, such an anomaly could indicate blood flowthrough a closed heart valve. Also, using multiple series of pulsesexposes the material under investigation to additional ultrasoundenergy. This additional energy may be considered undesirable.

BRIEF DESCRIPTION OF THE VARIOUS VIEWS OF THE DRAWING

[0009]FIG. 1 is a block diagram of an embodiment of the invention;

[0010]FIG. 2 is a flow diagram showing steps of an embodiment of theinvention;

[0011]FIG. 3 shows illustrative waveforms representing signals found ata step in the execution of an embodiment of the invention;

[0012]FIG. 4A shows an example of a demodulated signal spectrum from asingle channel associated with a single receiving transducer;

[0013]FIG. 4B shows an illustrative spectrum representing signals foundafter demodulation by an I/Q mixer;

[0014]FIG. 5 is a block diagram showing an embodiment of the inventionwherein harmonic signals for 2D imaging and fundamental signals forDoppler imaging are processed in parallel;

[0015]FIG. 6A shows steps involved in a method of the invention whereinharmonic signals are processed for 2D imaging;

[0016]FIG. 6B shows steps involved in a method of the invention whereinfundamental signals are processed for Doppler imaging;

[0017]FIG. 7A shows an illustrative spectrum representing signals foundafter processing using a multi-phase averager; and

[0018]FIG. 7B shows an illustrative spectrum representing signals foundafter demodulating the signal shown in FIG. 7A using a digital mixer.

SUMMARY OF THE INVENTION

[0019] The present invention includes systems and methods for performingparallel and multi-mode processing of ultrasound signals. For example,one method of parallel processing ultrasound signals is ultrasonicimaging including the steps of transmitting ultrasound pulses into amedia of interest that modifies the ultrasound pulses, receiving themodified ultrasound pulses at a sensor, generating signals responsive tothe received ultrasound pulses using the sensor, processing the signalsusing a plurality of imaging modes; interpreting the processed signalsto generate responsive positional data; and generating image data withno visible temporal anomalies using the positional data. Such an imageis said to be visibly temporally synchronized.

[0020] This method can be performed using an ultrasonic imaging systemincluding an ultrasound transducer for transmitting ultrasound pulsesinto a media of interest that modifies the ultrasound pulses, a sensor(which is optionally the same transducer used for transmitting) forreceiving the modified ultrasound pulses and generating analog signalsresponsive to the modified ultrasound pulses, an A/D converter forconverting the analog signals to digital data, a plurality of frequencyband preprocessors for preprocessing the digital data in parallel, andan echo-forming system for interpreting the preprocessed digital dataand generating positional data responsive to the preprocessed digitaldata. The echo-forming system optionally includes an area-formingsystem, a volume-forming system, or a multidimensional-forming system.

[0021] 1. A method of ultrasonic imaging comprising the steps of:

[0022] transmitting an ultrasound pulse into a media of interest suchthat the media of interest modifies the ultrasound pulse;

[0023] receiving the modified ultrasound pulse at a transducer;

[0024] generating signals responsive to the received ultrasound pulses;

[0025] processing the signals in parallel using a plurality of imagingmodes; and

[0026] interpreting the processed signals to generate responsivepositional data.

[0027] 2. The method of claim 1, wherein the step of interpreting theprocessed signals includes area-forming.

[0028] 3. A method of ultrasonic analysis comprising the steps of:

[0029] transmitting ultrasound pulses into a media of interest such thatthe media of interest modifies the ultrasound pulses;

[0030] receiving the modified ultrasound pulses at a transducer;

[0031] generating signals responsive to the received ultrasound pulses;

[0032] processing the signals using a plurality of imaging modes;

[0033] interpreting the processed signals to generate responsivepositional data, the positional data being temporally synchronized; and

[0034] generating image data, using the positional data.

[0035] 4. The method of claim 3, wherein at least one of the ultrasoundpulses is processed using at least two of the plurality of imagingmodes.

[0036] 5. The method of claim 3, further including the step ofdisplaying an image, without visible temporal anomalies, using the imagedata.

[0037] 6. A method of ultrasonic analysis comprising the steps of:

[0038] transmitting ultrasound pulses into a media of interest such thatthe media of interest modifies the ultrasound pulses;

[0039] receiving the modified ultrasound pulses at one or moretransducer;

[0040] generating signals responsive to the received ultrasound pulses;

[0041] preprocessing the signals using a plurality of frequency bandpreprocessors; and

[0042] interpreting the preprocessed signals to generate responsivepositional data.

[0043] 7. The method of claim 6, wherein the step of preprocessing thesignals is done in parallel.

[0044] 8. The method of claim 6, wherein the step of preprocessing thesignals is done in parallel and the step of preprocessing the signalsuses a plurality of imaging modes.

[0045] 9. The method of claim 6, further including the step ofgenerating image data using the positional data, and

[0046] wherein the step of preprocessing the signals is done inparallel.

[0047] 10. A method of ultrasonic analysis comprising the steps of:

[0048] transmitting ultrasound pulses into a media of interest such thatthe media of interest modifies the ultrasound pulses;

[0049] receiving the modified ultrasound pulses at one or moretransducer;

[0050] generating analog signals responsive to the received ultrasoundpulses;

[0051] converting the analog signals to digital data using an A/Dconverter;

[0052] preprocessing the digital data using a plurality of frequencyband preprocessors; and

[0053] interpreting the preprocessed digital data to generate responsivepositional data.

[0054] 11. The method of claim 10, wherein the step of preprocessing thedigital data is done in parallel.

[0055] 12. The method of claim 11, wherein the step of interpreting thepreprocessed digital data includes echo-forming.

[0056] 13. The method of claim 11, wherein the step of interpreting thepreprocessed digital data includes echo-forming and the echo-forminguses a area-forming module that includes a plurality of area-formers.

[0057] 14. The method of claim 11, further including the step ofproviding preprocessed digital data to one or more members of aplurality of area-formers from one or more members of the plurality offrequency band preprocessors.

[0058] 15. The method of claim 11, further including the step ofproviding the positional data to an image scan converter, wherein thepositional data is derived using a plurality of imaging modes.

[0059] 16. The method of claim 15, further including the step ofgenerating image data using the image converter and the positional data.

[0060] 17. The method of claim 15, further including the step ofgenerating image data using the image converter and the positional data,wherein the image data has no visible temporal anomalies.

[0061] 18. The method of claim 12, wherein the step of interpreting thepreprocessed digital data is performed in parallel by the echo-formingsystem.

[0062] 19. The method of claim 11, wherein the step of preprocessing thedigital data is performed with using a plurality of imaging modes.

[0063] 20. The method of claim 19, wherein the plurality of imagingmodes includes Doppler imaging.

[0064] 21. The method of claim 19, wherein the plurality of imagingmodes includes imaging using harmonic frequencies.

[0065] 22. The method of claim 10, wherein the step of preprocessing thedigital data is done in parallel, and

[0066] the plurality of frequency band preprocessors are responsive toencoding within the digital data.

[0067] 23. The method of claim 10, further including the step ofpost-processing the positional data in parallel using a plurality ofpost-processors.

[0068] 24. The method of claim 10, further including the step of storingthe digital data in an I/Q data buffer prior to the step ofpreprocessing the digital data.

[0069] 25. The method of claim 10, further including the step of storingthe digital data in a multi-channel data buffer, the step of storing ina multi-channel data buffer occurring after the step of preprocessingthe digital data and prior to the step of interpreting the preprocesseddigital data.

[0070] 26. A method of ultrasonic analysis comprising the steps of:

[0071] transmitting ultrasound pulses into a media of interest such thatthe media of interest modifies the ultrasound pulses;

[0072] receiving the modified ultrasound pulses at a transducer;

[0073] generating analog signals responsive to the received ultrasoundpulses;

[0074] converting the analog signals to digital data using an A/Dconverter;

[0075] preprocessing the digital data using a preprocessing module;

[0076] interpreting the preprocessed digital data and generatingresponsive positional data, using a plurality of echo-formers.

[0077] 27. The method of claim 26, wherein the step of preprocessing thedigital data uses a plurality of imaging modes in parallel.

[0078] 28. The method of claim 27, wherein the plurality of imagingmodes include harmonic imaging.

[0079] 29. The method of claim 26, wherein the plurality echo-formersinclude beamformers.

[0080] 30. The method of claim 26, wherein the plurality echo-formersinclude area-formers.

[0081] 31. The method of claim 26, wherein the step of interpreting thepreprocessed digital data is performed in parallel using the pluralityof echo-formers.

[0082] 32. The system of claim 26, further including the step ofproviding the positional data to a plurality of post-processors.

[0083] 33. The method of claim 26, further including the step ofgenerating image data using the image scan converter and the positionaldata, wherein the positional data is derived using a plurality ofimaging modes.

[0084] 34. The method of claim 26, further including the step of storingthe digital data in a multi-channel data buffer, the step of storing ina multi-channel data buffer occurring after the step of preprocessingthe digital data and prior to the step of interpreting the preprocesseddigital data.

[0085] 35. A method of ultrasonic analysis comprising the steps of:

[0086] transmitting a set of ultrasound pulses into a media of interestsuch that the media of interest modifies a plurality of pulses in theset of ultrasound pulses;

[0087] receiving the modified plurality of ultrasound pulses at atransducer;

[0088] generating signals responsive to the received pulses;

[0089] preprocessing the signals using a preprocessing module; and

[0090] interpreting the preprocessed signals to generate responsivepositional data using an echo-forming system, the positional dataincluding information derived from one pulse in the set of ultrasoundpulses, the derivation of information from the one pulse using aplurality of imaging modes.

[0091] 36. The method of claim 35, wherein the plurality of imagingmodes are applied using the preprocessing module.

[0092] 37. The method of claim 35, wherein the echo-forming systemincludes an area-forming module.

[0093] 38. The method of claim 35, wherein the echo-forming systemincludes an beam-forming module.

[0094] 39. A method of ultrasonic analysis comprising the steps of:

[0095] transmitting a set of ultrasound pulses into a media of interestsuch that the media of interest modifies a pulse in the set ofultrasound pulses;

[0096] receiving the modified ultrasound pulse at a transducer;

[0097] generating analog signals responsive to the received pulse;

[0098] converting the analog signals to digital data using an A/IDconverter;

[0099] preprocessing the digital data using a preprocessing module; and

[0100] interpreting, using an echo-forming system, the preprocesseddigital data to generate responsive positional data, the responsivepositional data being derived using a plurality of imaging modes.

[0101] 40. The method of claim 39, wherein the plurality of imagingmodes are used in parallel.

[0102] 41. The method of claim 39, further including the step ofproviding the positional data to a post-processing module including aplurality of post-processors.

[0103] 42. The method of claim 45, wherein the echo-forming systemincludes a beam-former.

[0104] 43. The method of claim 45, wherein the echo-forming systemincludes an area-former.

[0105] 44. The method of claim 39, further including the step of storingthe digital data in an I/Q data buffer prior to the step ofpreprocessing the digital data.

[0106] 45. The method of claim 39, further including the step of storingthe digital data in a multi-channel data buffer, the step of storing ina multi-channel data buffer occurring after the step of preprocessingthe digital data and prior to the step of interpreting the preprocesseddigital data.

[0107] 46. The method of claim 49, wherein the echo-forming systemincludes an multidimensional former.

[0108] 47. The method of claim 39, wherein the positional data istemporally synchronized.

[0109] 48. The method of claim 47, further including the step ofgenerating an image using the positional data, wherein the image has novisible temporal anomalies.

[0110] 49. An ultrasonic analysis system comprising:

[0111] an ultrasound transducer configured to transmit ultrasound pulsesinto a media of interest such that the media of interest modifies theultrasound pulses;

[0112] a transducer configured to receive the modified ultrasound pulsesand generating signals responsive to the modified ultrasound pulses;

[0113] a plurality of frequency band preprocessors configured topreprocess the signals in parallel; and

[0114] a echo-forming system configured to interpret the preprocessedsignals and generate responsive positional data.

[0115] 50. The system of claim 49, wherein the echo-forming systemincludes a plurality of beamformers, the plurality of beamformersconfigured to receive signals preprocessed using a plurality of imagingmodes.

[0116] 51. The system of claim 49, wherein the echo-forming systemincludes an area-forming module.

[0117] 52. The system of claim 49, wherein the echo-forming system isconfigured to include multidimensional-forming.

[0118] 53. An ultrasonic analysis system, comprising:

[0119] an ultrasound transducer configured to transmit ultrasound pulsesinto a media of interest, such that the media of interest modifies theultrasound pulses;

[0120] a transducer configured to receive the modified ultrasound pulsesand generate analog signals responsive to the modified ultrasoundpulses;

[0121] an A/ID converter configured to convert the analog signals todigital data;

[0122] a plurality of frequency band preprocessors configured topreprocess the digital data in parallel; and

[0123] an echo-forming system configured to interpret the preprocesseddigital data and generate positional data responsive to the preprocesseddigital data.

[0124] 54. The system of claim 53, further including an image scanconverter configured to receive the positional data, configured tocombine positional data derived using a plurality of imaging modes, andconfigured to use the combined positional data to generate compositeimage data.

[0125] 55. The system of claim 53, further including an image scanconverter configured to receive the positional data, configured tocombine positional data derived using a plurality of imaging modes, andconfigured to use the combined positional data to generate compositeimage data, the image data being used to generate an image withoutvisible temporal anomalies.

[0126] 56. The system of claim 53, wherein the echo-forming systemsincludes a plurality of beamformers.

[0127] 57. The system of claim 56, wherein the plurality of frequencyband preprocessors are configured to preprocesses the digital data in aplurality of imaging modes, the plurality of imaging modes includingDoppler imaging.

[0128] 58. The system of claim 57, wherein one or more beamformer withinthe plurality of beamformers is configured to receive preprocesseddigital data preprocessed by one or more of the plurality of frequencyband preprocessors.

[0129] 59. The system of claim 53, wherein the echo-forming systemsincludes a plurality of area-forming modules.

[0130] 60. The system of claim 59, wherein one or more area-formingmodule within the plurality of area-forming modules is configured toreceive preprocessed digital data preprocessed by one or more of theplurality of frequency band preprocessors.

[0131] 61. The system of claim 59, wherein the plurality of frequencyband preprocessors are configured to preprocess the digital data in aplurality of imaging modes, the plurality of imaging modes includingharmonic imaging.

[0132] 62. The system of claim 59, wherein the plurality of area-formingmodules are configured to interpret preprocessed digital data inparallel.

[0133] 63. The system of claim 53, wherein the plurality of frequencyband preprocessors are configured to preprocess the digital dataresponsive to encoding within the digital data.

[0134] 64. The system of claim 53, further including a post-processingmodule configured to receive the positional data, the post-processingmodule including a plurality of post-processors.

[0135] 65. The system of claim 53, further including an I/Q data bufferconfigured to receive the digital data prior to preprocessing.

[0136] 66. The system of claim 53, further including a multi-channeldata buffer configured to receive the preprocessed digital data andconfigured to deliver the received data to the echo-forming system.

[0137] 67. An ultrasonic analysis system comprising:

[0138] an ultrasound transducer configured to transmit ultrasound pulsesinto a media of interest such that the media of interest modifies theultrasound pulses;

[0139] a transducer configured to receive the modified ultrasound pulsesand configured to generate analog signals responsive to the modifiedultrasound pulses;

[0140] an A/D converter configured to convert the analog signals todigital data;

[0141] a preprocessing module configured to preprocessing the digitaldata; and

[0142] a plurality of area-formers configured to interpreting thepreprocessed digital data and generating positional data responsive tothe preprocessed digital data.

[0143] 68. The system of claim 67, wherein a member of the plurality ofarea-formers is configured to receive data preprocessed for Dopplerimaging.

[0144] 69. The system of claim 67, further including an image scanconverter configured to receive the positional data, configured tocombine the received positional data, and configured to use the combinedpositional data to generate composite image data, the positional databeing derived using a plurality of imaging modes.

[0145] 70. The system of claim 69, wherein the image data has no visibletemporal anomalies when displayed.

[0146] 71. The system of claim 67, wherein the digital data arepreprocessed using a plurality of parallel imaging modes.

[0147] 72. The system of claim 71, wherein the plurality of imagingmodes imaging using fundamental frequencies.

[0148] 73. The system of claim 67, wherein signal responsive to onepulse of the modified ultrasound pulses is converted to digital data,the digital data resulting from the one pulse being preprocessed using aplurality of parallel imaging modes.

[0149] 74. The system of claim 73, wherein the digital data resultingfrom the one pulse is interpreted by a plurality of area-formers.

[0150] 75. The system of claim 67, wherein the preprocessed digital datais interpreted in parallel.

[0151] 76. The system of claim 67, further including a post-processingmodule configured to receive the positional data, the post-processingmodule including a plurality of post-processors.

[0152] 77. The system of claim 67, further including an I/Q data bufferconfigured to receive the digital data prior to preprocessing.

[0153] 78. The system of claim 67, further including a multi-channeldata buffer configured to receive the preprocessed digital data, andconfigured to store the preprocessed data prior to the generation of thepositional data.

[0154] 79. An ultrasonic analysis system, comprising:

[0155] an ultrasound transducer configured to transmit a set ofultrasound pulses into a media of interest, the media of interestmodifying pulses in the set of ultrasound pulses;

[0156] a transducer configured to receive the ultrasound pulses modifiedby the media of interest, and configured to generate analog signalsresponsive to the modified ultrasound pulses;

[0157] an A/D converter configured to convert the analog signals todigital data;

[0158] a preprocessing module configured to preprocess the digital data;and

[0159] an echo-forming system configured to generate responsivepositional data from the preprocessed digital data, the responsivepositional data including information derived from at least one pulsewithin the set of ultrasound pulses, the derivation including aplurality of imaging modes executed in parallel.

[0160] 80. The system of claim 79, wherein the echo-forming systemincludes a volume-forming module.

[0161] 81. The system of claim 79, wherein the echo-forming systemincludes an area-forming system.

[0162] 82. The system of claim 81, wherein the echo-forming systemincludes a multidimensional-forming system.

[0163] 83. The system of claim 81, wherein the plurality of imagingmodes include harmonic imaging.

[0164] 84. The system of claim 81, further including a multi-channeldata buffer configured to receive the preprocessed digital data andconfigured to couple the received data to the echo-forming system.

[0165] 85. The system of claim 81, wherein the positional data istemporally synchronized.

[0166] 86. The system of claim 85, further including an image scanconverter configured to combine responsive the positional data generatedderived using different imaging modes and configured to form an imageusing the combined responsive positional data, the image having novisible temporal anomalies.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0167]FIG. 1 is a block diagram showing an embodiment of the inventiongenerally designated system 100. System 100 includes a waveformgenerator 110 that produces waveforms having a plurality of pulses.These pulses are optionally of differing or multiple frequencies. Theoutput of waveform generator 110 is coupled to a broad-beam transmitter115. Broad-beam transmitter 115 splits the input waveform into multiplechannels, amplifies the signal, and/or applies the delays required toform a broad-beam ultrasound wave. Broad-beam technology reduces thenumber of transmitted pulses required to image an area and enables useof area-forming techniques in place of prior art beam-forming methods.In an alternative embodiment broad-beam transmitter 115 is replaced by aprior art beam transmitter. The output of broad-beam transmitter 115 iscoupled through a multi-channel transmit/receive switch 120 and used todrive an ultrasound transducer 125. Ultrasound transducer 125 sendsultrasound pulses 127 into a media of interest 130. These ultrasoundpulses 127 are modified through attenuation, scattering, reflection,harmonic generation, or the like. Returning echoes are received bytransducer elements 128. Transducer elements 128, which are used todetect echoes, may be a part of ultrasound transducer 125, used togenerate ultrasound pulses 127. The detected signals include ultrasoundwith frequencies near the original transmitting frequency as well aswith other harmonic frequencies. Each of transducer elements 128converts the received ultrasound pulses into electrical signals andcouples these electrical signals to a distinct data channel 133.

[0168] After conversion to electrical signals, pulses are coupled tomulti-channel transmit/receive switch 120 from distinct data channels133. Transmit/receive switch 120 directs the electrical signals to amulti-channel analog amplifier 135. Analog amplifier 135 amplifies thesignals and couples them to a mixer 140 for demodulation. Mixer 140 canbe an analog mixer, a multi-channel mixer, a phase modulator, a timesignal multiplier and/or any other signal modulator known in the art.The demodulated signals are made up of in-phase and quardrature (I/Q)components. Each distinct data channel 133 is independently coupledthrough a filter 142.

[0169] In one embodiment filter 142 includes a multi-channel band-passfilter that selectively impedes specific frequency ranges. In thisembodiment, the resulting signals are digitized using a multi-channelA/D (analog to digital) converter 145 and are stored in an I/Q databuffer 150. I/Q data buffer 150 is multi-channel and can optionally beprogrammed to individually sum digitized signals received from eachdistinct data channel 133. I/Q data buffer 150 makes the stored dataavailable to a preprocessing module 160. In an alternative embodiment, adigital mixer 140 and/or digital filter 142 are optionally placed afterA/D converter 145.

[0170] An embodiment of preprocessing module 160 includes a plurality offrequency band preprocessors 162A-Z. These labels are arbitrarydesignations and not intended to limit the number of frequency bandpreprocessors 162 to twenty-six. Each frequency band preprocessor 162can process multiple data sets, from several or all of the distinct datachannels 133, stored in I/Q data buffer 150. The frequency bandpreprocessors are optionally differentiated by one or morecharacteristics. These differentiating characteristics include, forexample, the processing frequency range (frequency band), specificencoding within the processed signal, the mode of processing preformed,or the like. Signals, resulting from one or more transmit/receivecycles, are optionally combined, filtered, decoded, and/or modulated,prior to image formation. In one embodiment of the present invention,each frequency band preprocessor 162A-Z within preprocessing module 160can access all or part of the data within I/Q data buffer 150. Thefrequency band preprocessors 162A-Z may each take selected data andprocess it in parallel such that all of the data passed by band-passfilter 142 is optionally processed by at least one frequency bandpreprocessor 162A-Z. The preprocessed, multi-band, multi-channel signalsare optionally stored in multi-channel data buffer 165 and madeavailable to a series of area-formers 172 within an area-forming module170. In FIG. 1 area-formers 172 are individually designated 172A-Z.These labels are arbitrary designations and not intended to limit thenumber of area-former 172A-Z to twenty-six.

[0171] Embodiments of area-forming module 170 processes data stored inmulti-channel data buffer 165, or delivered directly from preprocessingmodule 160. The processing performed by area-forming module 170 includescalculating positional information regarding the source of signalswithin the media of interest 130. Each of area-former 172A-Z is capableof forming positional information covering an area using broad-beamtechnology, rather than just positional information along a line.Because preprocessing module 160 preprocesses the data, each ofarea-formers 172 optionally operates on a data set restricted to aspecific criterion or processed to accentuate a specific aspect of thedata. For example, in one embodiment area-former 172A receives datapreprocessed to identify moving components within media of interest 130.Area-former 172A, therefore, may operate on Doppler components of thetotal signal received by preprocessing module 160. In the sameembodiment, area-former 172B is disposed to process data combined afterprocessing by frequency band preprocessors 162A and 162B, each of whichpreprocesses data with a specific encoding. When input data is processedin parallel, each area-former 172A-Z generates output data with the sametime zero and temporal characteristics and the output data is temporallysynchronized. Because preprocessing module 160 optionally reduces thetotal amount of data, area-forming module 170 may operate on only partof the data received by preprocessing module 160 and calculations may,thus, be performed more rapidly. Data prepared by preprocessing module160 are parallel processed by area-forming module 170. The parallelaspect of the processing eliminates temporal delays between the outputsof the area-forming module 170 and allows different types of imagingmodes to be simultaneously executed. For example, data accentuatingmotion can be processed in one imaging mode at the same time that datarepresenting static structures is processed in another imaging mode.

[0172] In an embodiment output of area-forming module 170 is combined,or further processed, in a post-processor system 180. Since the outputsof area-forming module 170 can be based on signals recorded atsubstantially the same time, the output data, which can result fromseveral imaging modes, are combined without introducing temporal jitter.In various aspects of the invention post-processor system 180 alsocombines data from multiple broad-beam zones and prepares a single dataset for delivery to an image scan converter 190 for output on anoptional image display 192.

[0173]FIG. 2 is a flow diagram showing steps of an embodiment of theinvention utilizing the system illustrated by FIG. 1. In a waveformgeneration step 210 waveform generator 110 is used to produce a waveformhaving a series of pulses. These pulses are grouped as singlets, pairs,or larger combinations of pulses. The waveform generated in waveformgeneration step 210 optionally includes a plurality of characteristicssuch as frequencies, amplitudes, pulse widths, phases, or variationthereof. These characteristics are optionally used to encode thewaveform. As an example, FIG. 3 illustrates the waveform including aseries of pulse pairs having opposite phase.

[0174] In a broad-beam generation step 215, broad-beam transmitter 115processes the waveform generated by waveform generator 110. In variousaspects of the invention the processing by broad-beam transmitter 115includes amplifying the waveform, separating the waveform among distinctdata channels 133, applying delays and weightings to each distinct datachannel 133, and the like. Broad-beam generation step 215 furthereffectuates coupling the processed waveform within each distinct datachannel 133 to multi-channel transmit/receive switch 120 and tomulti-element ultrasound transducer 125. In a transmit ultrasound step220 each element of ultrasound transducer 125 emits ultrasound pulses127 using the processed waveforms. Since the present inventionoptionally includes broad-beam technology, the number of pulses requiredto cover the imaging area can be significantly fewer than the numberrequired to cover a similar area using conventional beam-forming methodsknown in the art.

[0175] In an pulse propagation step 225 ultrasound pulses 127 propagatethrough media of interest 130. Variations in media of interest 130 causeechoes to be generated and ultrasound pulses 127 to be altered. In anecho receiving step 230 returning ultrasound signals are received byultrasound transducer 125 using transducer elements 128. Transducerelements 128 receive the returning ultrasound signals at the frequencynear or at the frequencies of ultrasound pulses 127 and/or at harmonicsthereof. Each receiver generates signals in at least one of distinctdata channel 133 and the signals of each distinct data channel 133 arecoupled through transmit/receive switch 120 to analog amplifier 135.From echo receiving step 230 through a post-processing step 275 alloperations are optionally performed on distinct data sets, such as setdistinguished by different analysis modes, in parallel.

[0176] An amplification step 235 uses a low-noise analog amplifier 135to amplify distinct data channel 133 signals. In an I/Q demodulationstep 240, each channel is processed by mixer 140 that demodulates thesignals. FIG. 4A illustrates an example of a resulting demodulatedsignal spectrum from a single channel associated with a single receiver.Signal components can be found near the frequency (f₀) at which theultrasound was transmitted and at harmonics of the transmitted frequency(2f₀, 3f₀, or the like). In an embodiment of the invention, mixer 140demodulates the components of the signal at the fundamental frequency(f₀) to a base-band frequency (f_(b)) and demodulates the 2^(nd)harmonic components of the signal to a new frequency (f_(b)+f₀). Theresult is illustrated in FIG. 4B. In a filtering step 245 each signal isoptionally coupled through filter 142. Filter 142 applies a high-pass,low-pass, or band-pass filter to the signal. The type of filtering isselected as a function of the expected use of the signal.

[0177] In an A/D conversion step 250 the signal in each distinct datachannel 133 is converted from the analog to the digital domain by A/Dconverter 145. In an alternative embodiment AID conversion step 250occurs prior to demodulation step 240 or filtering step 245. In a datastorage step 255, the digitized data from each channel is stored in I/Qdata buffer 150. I/Q buffer 150 optionally sums the digital signalsresulting from a plurality of pulses. The summed, “raw,” data is sampledat the output of the I/Q data buffer 150. Under selected summation andphase conditions, the summation process results in an averageapproaching zero for some components of the signals.

[0178] In a data preprocessing step 260 preprocessing module 160 readsdata from I/Q data buffer 150 and processes it using one or more offrequency band preprocessors 162A-Z. Each frequency band preprocessor162A-Z can access all of the data available in I/Q data buffer 150.However, depending on the type of imaging mode desired, each frequencyband preprocessor 162A-Z can also be operated to processes only asegment of the data. In various aspects of the invention, these segmentsare divided by transducer channel, frequency range, or encoding. Invarious embodiments frequency band preprocessors 162A-Z apply a varietyof processing routines to the data. In an illustrative example, half ofthe frequency band preprocessors 162A-Z are configured to process dataassociated with Doppler signals while the other half are configured toprocess signals associated with static structures. Thus, in theseembodiments, preprocessing module 160 processes the data stored in I/Qdata buffer 150 in multiple modes, in multiple frequency bands, withmultiple encodings, and/or in multiple independent data channels. Sincepreprocessing module 160 consists of multiple independent frequency bandpreprocessors 162A-Z, processing can occur in parallel.

[0179] In an embodiment of the invention signals are processed byfrequency band preprocessors 162A-Z as a function of encoding includedwithin the signal. For example, if waveform generator 110 producespulses at two or more distinct frequencies, the returned (encoded)ultrasound echoes can be differentiated (decoded) by their frequency.This ability to differentiate allows pulses to be sent into the materialunder investigation at a rate faster than un-encoded pulses, since asecond set of pulses can be sent before the first is received. Usingthis encoding the pulse transmit rate and the collection of data is notlimited by the roundtrip time of a pulse. The pulse roundtrip time isthe time between transmission of a pulse and the detection of allresulting echoes. Frequency band preprocessors 162A-Z can beindividually arranged to select and process signals resulting from oneor more of distinct frequency bands.

[0180] After preprocessing, data is optionally stored in multi-channeldata buffer 165 in a data storing step 265. This step enables furtherdata manipulation, such as averaging and synchronization betweenpreprocessing module 160 and area-forming module 170. If the product ofthe number of preprocessing modes, frequency bands, and data channels islarger than the number of frequency band pre-processors then some of thechannels can be preprocessed in parallel and the results are stored inmulti-channel data buffer 165. Following this preprocessing process,another set of channels is optionally preprocessed and stored. Thepreprocessing process can be repeated until all channels have beenpreprocessed and stored. The use of multi-channel data buffer 165further enables the implementation of a larger number of parallelpreprocessing modes, frequency bands, encoding, and the like.

[0181] In an area-forming step 270 preprocessed data is used to performparallel area-forming calculations using area-forming module 170.Area-forming module 170 includes a plurality of area-former 172A-Z. Eacharea-former 172A-Z can be enabled to identify locations of echo sourcesfrom data generated by an individual frequency band preprocessor 162A-Z,For example, in an embodiment of the present invention, area-former 172Ais configured to process data preprocessed by frequency bandpreprocessor 162A. In another embodiment of the invention, area-former172A is configured to process data combined in multi-channel data buffer165 after parts of the data are separately preprocessed by frequencyband preprocessor 162B and frequency band preprocessor 162A.Preprocessing the data potentially reduces noise, undesirable signalcomponents, and the total amount of data within each data channel.

[0182] The existence of several area-former 172A-Z within area-formingmodule 170 enables parallel processing of data associated with multipleimaging modes. For example, in one embodiment area-former 172A isconfigured to process data associated with moving echo sources andarea-former 172B is configured to process data associated with staticecho sources. In another embodiment area-former 172 A is configured toprocess data with encoding type A and area-former 172B is configured toprocess data with encoding type B, where encoding types A and B are anytwo distinguishable encoding schemes.

[0183] In an optional post-processing step 275 the output ofarea-forming module 170 is post-processed by post-processing system 180.Post-processing can include one or more elements such as encoding ofdata generated using different modes, sum and difference calculationsbetween data generated using different modes, calculation of differencesamong data recorded at different times, differential and integralcalculations, or the like. Post-processing system 180 can also combinedata derived from multiple transmit zones to produce data sets coveringan expanded area. Post-processing generates at least data representingsome attribute of the signal as a function of a coordinate system.

[0184] In an optional image scan conversion step 280 an image isprepared using image scan converter 190. The image optionally includesmotion video and/or false color representations of the encodingdeveloped in post-processing step 275. For example, in one embodiment ofthe invention velocities of detected materials are calculated and colorsare chosen so as to visually convey the range and distribution ofvelocities. In another embodiment of the invention static components ofthe material of interest are shown using a color scheme designed to showmaterial ultrasound reflectivity.

[0185] The above process is optionally repeated for multiple transmitzones until an entire field of view is covered. For example, seeco-pending U.S. patent application Ser. No. ______ entitled “BlockSwitching in Ultrasound Imaging.” The final images of multi-mode and/ormulti-band signals are combined and scan-converted to an appropriatedisplay format by image scan converter 190.

[0186] In an optional display step 285 the image prepared in image scanconversion step 280 is displayed using image display 192. The finalimages are displayed with little or no time delay or time lag betweenvarious components of the image that result from different imaging modeor frequency bands.

[0187] In the present invention more than one imaging mode is optionallyperformed on a single set of data produced from a single set oftransmitted ultrasound pulses. In these embodiments a single set ofultrasound pulses, are used in parallel to generate echo location databased on multiple analysis modes. In several embodiments, parallelmulti-mode imaging creates a visibly temporally synchronized image,thereby eliminating time jitter (temporal anomalies) associated withprior art methods of serial generation of echo data in multi-modeimaging. Multi-band preprocessing and area-forming enables theseparation of signals based on encoding characteristics. For example,images, or other echo location data, produced from separate frequencybands can be formed in parallel and compounded together to decreasespeckle noise without reduction of frame rate.

[0188]FIG. 5 is a block diagram showing an embodiment of the inventionwherein harmonic signals for 2D imaging and fundamental signals forcolor Doppler imaging are produced and processed in parallel. Thisembodiment executes the two different data processing modes at the sametime. In the illustrative example of FIG. 5, one of the modes isdesigned to perform high-resolution 2D harmonic tissue imaging, whilethe other mode is designed to perform color Doppler flow imaging. Bothmodes use the same set of data that are produced from a series of pulsefirings and collected at I/Q data buffer 150. Alternative embodimentsoptionally include more than two different analysis modes executed inparallel.

[0189] In the 2D harmonic tissue imaging mode, data is copied from I/Qbuffer 150 to frequency band preprocessor 162A. In this mode, frequencyband preprocessor 162A is used to process harmonic signals to produce ahigh resolution 2D tissue image. Frequency band preprocessor 162A isconfigured to include multi-pulse averager 510, digital mixer 520, andbase-band filter 530. The results of the preprocessing are optionallystored in multi-channel data buffer 165 and coupled to area-former 172Ato reconstruct echo location data (image). The echo location data(image) is coupled to post-processor 182A. In this embodiment,post-processor 182A includes a magnitude detector 560 and 2D imageprocessor 570.

[0190] In the Doppler flow imaging mode, data is copied from I/Q buffer150 to frequency band preprocessor 162B. In this embodiment, this datais the same data copied from I/Q buffer 150 for use in a parallel 2Dharmonic tissue imaging mode. In the Doppler flow imaging mode,frequency band preprocessor 162B is configured to include a clutterfilter 540 and a base-band filter 550. Using these elements, frequencyband preprocessor 162B processes the fundamental frequency signal todetect moving targets within media of interest 130. After optionalstorage in multi-channel data buffer 165 and processing by area-former172B, the re-constructed echo location data is coupled to postprocessor182B, which includes a Doppler flow estimator 580 and a color flow imageprocessor 590. Image scan converter 190 combines the echo location datagenerated using both processing modes and converts the combined datainto an appropriate display format to form the final image. The finalimage is optionally displayed using image display 192.

[0191] The various elements 510 through 590 introduced in FIG. 5 areoptionally implemented using software. Thus, while preprocessor 162Aincludes multi-pulse averager 510, Digital mixer 520, and base-bandfilter 530 in one instance of an embodiment, in a subsequent instance ofthe same embodiment preporcessor 162A may be reconfigured via softwareto include instead clutter filter 540 and base-band filter 550.Post-processor 182A is optionally configurable through software in aanalogous manner.

[0192]FIG. 6 includes two flowcharts showing processes enabling twodifferent imaging modes that can be executed in parallel utilizing theelements shown in FIG. 5. FIG. 6A shows steps involved in a method ofthe invention wherein harmonic signals are processed for 2D imaging.FIG. 6B shows steps involved in a method of the invention whereinfundamental signals are processed for Doppler imaging. Both flowchartsstart from step 255 and conclude at step 280 of FIG. 2.

[0193] In the method illustrated by FIG. 6A, data preprocessing step 260includes a data averaging step 610, a digital modulation step 620, and abase-band filtering step 630. In data averaging step 610, multi-pulseaverager 510 (FIG. 5) reduces or eliminates fundamental frequencycomponents by averaging multiple received signals generated usingmultiple pairs of phase-inverted transmitting pulses. Since the 2^(nd)harmonic component of the received signals from these phase-invertedpulse sequence are in-phase, the signal-to-noise ratio of the 2^(nd)harmonic component is enhanced by the averaging process. An illustrationof resulting signals is shown in FIG. 7A. Signals at the fundamentalfrequency are essentially cancelled and the 2^(nd) harmonic signals areenhanced. In alternative embodiments wherein the transmitting pulsesequence is not phase-inverted, the signal average simply serves toimprove signal-to-noise ratio. In digital demodulation step 620 thedigital mixer 520 demodulates the 2^(nd) harmonic component down tobase-band frequency. Possible resulting signals are illustrated in FIG.7B. In base-band filtering step 630, base-band filter 530 is used tofilter out any residual fundamental frequency component and other noiseoutside the base-band, while preserving the demodulated 2^(nd) harmonicsignal.

[0194] After base-band filtering step 630, the data are optionallystored, in a data storing step 265, in multi-channel data buffer 165. Inan area-forming step 270 the pre-processed 2^(nd) harmonic componentsare coupled to area-former 172A and echo location data is re-constructedfor 2D tissue image.

[0195] In the method illustrated by FIG. 6A, post-processing step 275includes a signal magnitude detection step 640 and a 2D image processingstep 650. Magnitude detection step 640 includes I/Q signal-to-magnitudeconversion and log-compression. 2D image processing step 650 optionallyincludes operations such as adjustment of gain and dynamic range,spatial and/or temporal filtering, and the like.

[0196] In the method illustrated by FIG. 6B preprocessing step 260includes a clutter filtering step 660 and a base-band filtering step670. In clutter filtering step 660, clutter filter 540 is applied to thesame multiple signals collected for harmonic tissue imaging to removesignals resulting from stationary and slow-moving sources within themedia of interest 130. In base-band filtering step 670 base-band filter550 is used to extract the cultter-filterd fundamental frequencycomponent and remove any noise outside base-band. Preprocess data step260 is followed by optional store data step 265 and area-forming step270.

[0197] In the method illustrated by FIG. 6B a post-processing step 275includes a Doppler parameter estimation step 680 and a Doppler parameterpost-processing step 690. In Doppler parameter estimation step 680,Doppler flow estimator 580 calculates flow parameters such as Dopplervelocity, Doppler velocity variance, Doppler energy, and the like. Thesecalculations are optionally accomplished using auto-correlation methodsknown in the art. In Doppler parameter post-processing step 690 colorflow image processor 590 can use thresholds, noise reduction, smoothing,color coding and/or other image processing techniques to generate acolor image conveying information of the Doppler parameters of interest.

[0198] The methods illustrated by FIGS. 6A and 6B are optionallyperformed in parallel. The results of both processes are combined in asingle image data set in image scan conversion step 280 (FIG. 2). Thissingle image data set is displayed in display step 285 using imagedisplay 192. Since both imaging modes are executed in parallel and usethe same set of received data the outputs are generated more quicklythan serial execution and the images produced using each imaging modeare temporally synchronized with each other. Quicker image generationenables a higher frame rate. The synchronization of data collection formultiple imaging modes can eliminate or reduce temporal anomalies withina resulting composite image. Encoded data arising from multipletransmitted pulses are optionally added together to improvesignal-to-noise ratios.

[0199] Steps 260 through 275 optionally include additional andalternative imaging modes such as fundamental imaging, color Dopplerimaging, harmonic imaging, spectral Doppler imaging, and/or any otherultrasound imaging mode. Combinations of three or more parallel modesare also possible in alternative embodiments. For example, one set ofthree parallel modes includes harmonic tissue imaging, color Dopplerimaging, and spectral Doppler imaging. Alternatively, another set ofthree parallel modes includes harmonic tissue imaging, Doppler tissueimaging and color Doppler imaging.

[0200] In practice the above methods are optionally applied to a seriesof zones covering an image field of view within media of interest 130.Each zone can be processed independently and an image of the combinedzones can be constructed by image scan converter 190. In each zone a setof N pulses is used to generate data using parallel processing. For Kzones a total of K*N pulses are required to form a complete image. Forsome imaging modes the minimum value of N is two and for other imagingmodes the minimum value of N is one. Increasing the number of processingmodes does not necessarily increase the number of required pulses. Also,minimizing power consumption extends the lifetime of limited powersources, such as batteries, and enables the use of battery powered,single or multi-mode, instruments with increased operating times.

[0201] The parallel processing architecture described in this inventionresult in very fast data processing speeds. The pre-processing of rawI/Q data optimizes the input signal and improves signal to noise ratiosprior to area formation. This optimized input signal improves thequality of area formation and precision of the resulting image data.

[0202] From the description of the preferred embodiments of the processand apparatus set forth herein, it will be apparent to one of ordinaryskill in the art that variations and additions to the embodiments can bemade without departing from the principles of the present invention. Forexample, preprocessing module 160 and area-forming module 170 can beused for the processing of ultrasound data obtained through alternativemeans. In various embodiment area formers 172 are replaced byalternative echo-forming systems, such as series of parallel multi-linebeamformers, individual examples of which are known in the art.Echo-forming systems include beam-forming systems, area-forming systems,volume-forming systems, and multidimensional-forming systems. Theultrasound system of the present invention may be used to image a widerange of materials.

We claim:
 1. A method of using ultrasound to analyze a media ofinterest, comprising the steps of: transmitting an ultrasound pulse intothe media of interest, the ultrasound pulse being modified by the mediaof interest; receiving at a transducer the modified ultrasound pulse;generating signals in response to the received modified ultrasoundpulse; parallel processing the signals using a plurality of imagingmodes; and generating positional data responsive to the parallelprocessed signals.
 2. The method of claim 1, wherein the step ofgenerating positional data includes area-forming.
 3. A method of usingultrasound to analyze a media of interest, comprising the steps of:transmitting a plurality of ultrasound pulse into the media of interest,the ultrasound pulses being modified by the media of interest; receivingat one or more transducers the modified ultrasound pulses; generatinganalog signals in response to the received modified ultrasound pulses;converting the analog signals to digital data using an A/D converter;preprocessing the digital data using a plurality of frequency bandpreprocessors; and generating positional data responsive to thepreprocessed digital data.
 4. The method of claim 3, wherein digitaldata resulting from an individual member of the plurality of ultrasoundpulses is processed using a plurality of imaging modes.
 5. The method ofclaim 3, further including the step of displaying an image visiblytemporally synchronized using the generated positional data.
 6. Themethod of claim 3, wherein the step of preprocessing the digital data ispreprocessed in parallel.
 7. The method of claim 3, wherein thepositional data is generated using echo-forming.
 8. The method of claim3, wherein the positional data is generated using echo-forming and theecho-forming uses an area-forming module that includes a plurality ofarea-formers.
 9. The method of claim 3, further including the step ofproviding preprocessed digital data to one or more members of aplurality of area-formers from one or more members of the plurality offrequency band preprocessors.
 10. The method of claim 6, furtherincluding the step of providing the positional data to an image scanconverter, wherein the positional data is generated using a plurality ofimaging modes.
 11. The method of claim 10, further including the step ofgenerating image data using the image scan converter and the positionaldata.
 12. The method of claim 10, further including the step ofgenerating image data using the image scan converter and the positionaldata, wherein the image data is visibly temporally synchronized.
 13. Themethod of claim 6, wherein the step of preprocessing the digital data isperformed using a plurality of imaging modes.
 14. The method of claim13, wherein the plurality of imaging modes includes Doppler imaging. 15.The method of claim 13, wherein the plurality of imaging modes includesimaging using harmonic frequencies.
 16. The method of claim 3, whereinthe step of preprocessing the digital data is done in parallel, and theplurality of frequency band preprocessors are responsive to encodingwithin the digital data.
 17. The method of claim 3, further includingthe step of post-processing the positional data in parallel using aplurality of post-processors.
 18. An ultrasonic analysis systemcomprising: an ultrasound transducer for transmitting ultrasound pulsesinto a media of interest such that the media of interest modifies theultrasound pulses; a transducer for receiving the modified ultrasoundpulses and generating signals responsive to the modified ultrasoundpulses; a plurality of frequency band preprocessors for preprocessingthe signals in parallel; and an echo-forming system for generatingpositional data responsive to the preprocessed signals.
 19. The systemof claim 18, wherein the echo-forming system includes a plurality ofbeamformers configured to receive signals preprocessed using a pluralityof imaging modes.
 20. The system of claim 18, wherein the echo-formingsystem includes an area-forming module.